Case erectors and case sealers are automated machines that open and seal “cases,” which in some applications are cardboard boxes. For example, cardboard boxes can be purchase new, or obtained for reuse, in a “knocked down” (i.e. a folded flat) configuration. The case erector opens the box so that product (e.g. goods and merchandise) may be inserted. A case sealer then seals the case (e.g. the case sealer applies tape or glue to flaps of the box).
In one application, a case sealer can close flaps of a cardboard or similar case in a “fan fold” configuration. A typical case or box has four flaps that comprise either (or both) the top and bottom of the box. Either or both of the top and the bottom flaps can be closed in a fan fold manner. Each flap is attached to the box along a fold. Each flap has an edge that is opposite the fold. The opposite edge has a left corner and a right corner. When the box is closed in a fan fold manner, the right corner of each flap is under the left corner of the adjacent flap to the right, or the left corner of each flap is under the right corner of the adjacent flap to the left. Thus, a fan fold configuration holds the flaps of a box closed without tape or glue. It is probably the case that the term “fan fold” derives from the resemblance of the flaps of the case, once folded, to resemble the blades of a air-moving fan, in that each flap is somewhat tilted in relation to other flaps.